Interviewing film stars at premieres has turned into a contemporary version of the medieval trial by ordeal; in this case it is trial by microphone. In front of a roaring crowd, under burning, flashing lights, the poor actor is goaded, with the microphone as a jabbing cow prod, into making ever more indiscreet remarks to feed the insatiable curiosity of the fans.

No matter how silly the questions, the poor victim must remain charming and keep repeating titillating soundbites, without ever actually being injudicious or displeasing the capricious movie-going masses. One can only sympathise.

All the same I was absolutely astonished by Keira Knightley, the beautiful Lizzie Bennet in the new film of Jane Austen’s Pride and Prejudice, during her trial by microphone just before the premiere in Leicester Square last week. Maddened perhaps by a particularly annoying young man, this bewitching creature offered up to her interviewer the thought that if a man sees this new film with a girlfriend he is guaranteed to get laid afterwards.

What on earth, I immediately wondered, would the blessed Jane Austen herself have made of that? It would surely have been a great shock to hear her own favourite creation described as a sexual aid, or rather — since the term sex aid cannot have featured much in her vocabulary — to hear Pride and Prejudice spoken of an incitement to such activity.

Of course Jane Austen’s novels are about sex, or rather, among other things, about how people deal with their sexual desires within a particular social convention. But even so, I cannot imagine that she would be pleased to hear Pride and Prejudice warmly recommended as certain to inflame sexual desire forthwith. That is the function of pornography, and whatever Jane Austen may have thought about pornography, it is a fair bet that she would not have wanted to be seen as a pornographer herself, however soft.

To be fair to Keira Knightley, and to the film itself, which has already been much admired, it is actually true that going to the cinema itself does tend to lead to sex anyway. Some rather startling American sociological studies I read in the early 1970s made this point and it is the kind of point one doesn’t forget. If a great deal of sexual activity does follow hard upon the mass distribution of this film, starting this week, one need not necessarily hold Jane Austen responsible.

All the same, I did wonder very much what Jane Austen would think of the hyper-sexualised temper of the times, which that moment in Leicester Square somehow encapsulated. Wondering what she’d think is something I often do anyway. I’m one of those countless thousands who re-read her novels often, and think of her as my own particular friend. My sense that I know her well is, I admit, an illusion, but I think one can be fairly sure that Jane Austen would be astonished by the way we are, and rather contemptuous.

It’s absolutely clear that Jane Austen placed enormous value on self-discipline, discretion, modesty and reticence — a word almost never used today. All her heroines have to learn to temper their passionate feelings with these virtues. Sensibility (feeling) must be controlled by sense (reason and judgment). Those characters who don’t discipline their feelings, who don’t understand what proper feeling is, or who behave self-indulgently are mocked and even despised. So is self-centredness; Austen’s heroines have to find a difficult balance between the needs of the self and the demands of society.

It might not perhaps have surprised Jane Austen to see the masses going about drunkenly brawling, shrieking and vomiting in public, or talking ceaselessly about their tedious perversions and their tedious daily lives on reality TV. She lived at the time of the French revolution and of the notorious libertinism of the English upper classes. She wasn’t priggish or ignorant either — she gives one of her most attractive characters a notorious double entendre in Mansfield Park, when, talking about her uncle the admiral, she refers very suggestively to “rears and vices” in the navy.

What would have surprised Jane Austen is the way the respectable middle classes have also abandoned the virtues of her world, as well as the upper and lower orders. The way we live now — with people of all classes ceaselessly exposing their flesh and their secrets in public, with a licentious abuse of sexual freedom, with an unself-critical preoccupation with the self, with the fading of a sense of duty, with a coarsening of manners — is at odds with everything Jane Austen felt mattered.

It is a mystery to me why Pride and Prejudice is one of the nation’s most loved novels; apart from the romantic comedy, it seems to me to stand for everything that most people today have rejected.

I think that’s how she herself would have felt, too. What I would love to know is how the same Jane Austen would feel and think if she were a contemporary, born into our world. Then her judgments would surely be very different. Many of her 19th-century views on modesty, chastity and worldly prudence were both a conventional and a considered response to the predicament of women at the time. A respectable marriage was everything, even to an offensive buffoon like Mr Collins in Pride and Prejudice; the alternative was spinsterhood, dependence, loss of caste and very likely poverty.

So feelings, and sexual feelings, had to be subordinated to the need to be settled in a proper establishment, though Jane Austen herself, intriguingly, first accepted and then turned down a very respectable suitor. It would be wonderful to know how real independence from all that — financial and sexual — would have changed her and what she might still have to teach her admirers.

Counter-factual history is just guessing, of course. But there are informed guesses. And though I think Jane Austen today would have loved the freedom women have now, and would have lost her very mild and conventional Anglican faith and might even have been a lesbian, she still, I am convinced, would in a very unfashionable way, have valued self-discipline and discretion.

At least she would not have dreamt of talking in public about getting laid.

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